Atomic Mass

Atomic Mass

1. Atomic mass is the mass of an atom

2. A single atom has a set number of protons and neutrons, so the mass won't change, Electrons contribute so little mass they aren't counted

3. Atomic Weight is the average weight of the mass of all the atoms of an element, based on the abundance of isotopes.

   • The atomic weight can change because it depends on our understanding of how much of each isotope of an element exist.

4. Both atomic mass and atomic weight rely on atomic mass units (amu), which is 1/12th the mass of an atom of carbon-12 in it's ground state